1. Field of the Invention
This invention relates to an audio data reproduction system and an audio data reproduction method which transfer audio data loaded from an external storage medium, such as compact disc (CD), into a personal computer (PC) to a mobile terminal and reproduce the audio data at the terminal, and an electronic device used in the system.
2. Description of the Related Art
Audio data recorded in an external recording medium, such as a compact disc (CD), is loaded into a personal computer (PC) and the audio data loaded into the PC is further transferred to a mobile terminal, which makes it easy to carry around and reproduce the audio data transferred to the mobile terminal.
When the audio data recorded on the CD has been protected under copyright law, a person who has purchased the CD through the proper channel is permitted to copy the audio data for personal use only. For this reason, if having bought the CD through the proper channel, the user can transfer the audio data from the user's PC to a mobile terminal and use the data.
However, transferring and recording (copying) the audio data loaded into the person's PC to another person's mobile terminal and using the data are regarded as unauthorized use. To overcome this problem, the following method has been considered: a unique encryption key is generated between a device (e.g., PC) on the audio data transmission side and a device (e.g., mobile terminal) on the receiving side, the audio data is encrypted using the encryption key and the encrypted data is transmitted, and the received audio data is decrypted using the encryption key and reproduced, thereby preventing unauthorized use.
In this method, since all of the audio data are to be encrypted, this imposes a heavier burden of encryption on the device on the audio data transmission side and further a heavier burden of decryption on the device on the receiving side. Consequently, both of the devices require sophisticated processors.
To avoid this problem, an audio data reproduction apparatus and an audio data reproduction method have been considered which transmit audio data without encrypting a part of the audio data, thereby alleviating the burden of encryption and decryption as disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2005-114931.
However, in the conventional audio data reproduction apparatus and audio data reproduction method, the audio data still has to be encrypted and decrypted, which makes the burden heavier. For this reason, in an electronic device with a not-so-high performance processor, for example, in an electronic dictionary, it is impossible to take measures to reliably prevent the externally loaded audio data from being used fraudulently.